GST Sales Categories, Tax Invoices, and Mixed Supplies: A Practical Guide for Australian Businesses

Not every sale is taxed the same way under Australia's GST system. Sales fall into one of three categories: taxable, GST-free, or input taxed. The category determines whether you charge GST, whether you can claim GST credits on related purchases, and how the sale is reported on your BAS. Most BAS errors start with a misclassified sale, not a missed BAS date.

This guide explains how to classify your sales correctly, when you need to issue a tax invoice and what it must contain, how to handle mixed supplies where different items on the same invoice have different treatments, and the calculation rules that catch business owners out most often. For GST registration, BAS due dates, and the general reporting cycle, our Small Business Tax Compliance article covers the ground in more depth.

Key takeaways

• Three sales categories: taxable (charge GST, claim GST credits), GST-free (no GST charged, still claim GST credits on related purchases), and input taxed (no GST charged, no GST credits claimable).
• GST is 10% of the GST-exclusive price, or one-eleventh of the GST-inclusive price. A $1,100 sale GST-inclusive contains $100 of GST.
• You must issue a tax invoice within 28 days of a customer's request for taxable sales of $82.50 (GST-inclusive) or more. Sales of $1,000 or more require additional information including the buyer's identity or ABN.
• Food, health, education, exports, childcare, and certain farm inputs are the main GST-free categories, but each has precise boundaries. Prepared hot food and takeaway meals are taxable even in a business that also sells GST-free basic food.
• Residential rent and most financial supplies are input taxed. Input taxed sales do not allow GST credits on related purchases, which is a different outcome from GST-free sales.
• Mixed supplies (one invoice covering items with different GST treatments) need the GST treatment of each item identified separately.
• If your business is not registered for GST, your documents are invoices, not tax invoices. Labelling a non-GST invoice as a tax invoice is a compliance breach.

The three categories of sales

Every sale a GST-registered business makes falls into one of three categories. Getting this right at the start of a transaction is much easier than correcting it at BAS time.

Taxable sales

Most sales a typical Australian business makes are taxable. GST is charged at 10% on top of the GST-exclusive price, or is included at one-eleventh of the GST-inclusive price. The business collects the GST from the customer, reports it in the BAS, and remits the net amount to the ATO after claiming GST credits on business purchases.

A sale is taxable when all four of the following are met: it is made for payment, it is made in the course of an enterprise, it is connected with Australia, and it is not GST-free or input taxed. Most everyday trading sales by Ipswich businesses meet this test: trade services, professional fees, retail goods, commercial rent, restaurant meals, equipment hire, and so on.

GST-free sales

GST-free sales are still reported on your BAS, but no GST is charged to the customer. The important feature of GST-free sales is that the business can still claim GST credits on purchases related to making those sales. This is what distinguishes GST-free from input taxed.

The main GST-free categories are:

• Basic food for human consumption (bread, milk, fresh fruit and vegetables, plain flour, tea and coffee not in beverage form). Prepared food, hot food, and food for immediate consumption are taxable.
• Most health services supplied by a recognised health professional, where the service is generally accepted in the relevant profession as necessary for appropriate treatment.
• Most education courses provided by recognised institutions, including primary, secondary, tertiary, and certain professional and trade courses. Not every course qualifies.
• Childcare services supplied by an approved provider.
• Exports, where the goods leave Australia within 60 days of the earlier of payment or invoice, or the services are supplied to a non-resident outside Australia.
• Certain sales of going concerns, where both parties agree in writing and specific conditions are met.
•  Some farming inputs, water and sewerage services, and cars for eligible disabled people.

The list looks broad, but each category has strict tests. A café selling bread loaves sells GST-free basic food. The same café selling a toasted sandwich made from that bread sells taxable prepared food. A GP charging for a standard consultation is making a GST-free health sale. The same GP selling a skincare product from reception is making a taxable retail sale.

Input taxed sales

Input taxed sales are the third category, and the most commonly misunderstood. No GST is charged on the sale, but the business also cannot claim GST credits on purchases related to making the sale. The business effectively absorbs the GST on its costs.

The main input taxed categories are:

• Residential rent (renting out a house, apartment, or similar residential premises).
• Sales of existing residential premises (new residential premises are generally taxable).
• Most financial supplies (interest on loans, dividends, shares, foreign exchange, superannuation contributions).

The input taxed status of residential rent is a common trap for property owners. A landlord renting out a house in Ipswich does not charge GST on the rent and does not register that activity for GST, but also cannot claim GST credits on the water heater repair, the property management fee, or the insurance premium. By contrast, a commercial landlord renting out a warehouse or retail space is making a taxable sale, charges GST on the rent, and claims GST credits on related expenses.

Common classification traps

Food businesses

Food is where businesses get classification wrong more often than anywhere else. The rule that food is GST-free applies only to basic food for human consumption, eaten away from the point of sale in its unprepared state. The moment food is prepared, heated, or sold for immediate consumption, it becomes taxable.

A loaf of bread in a grocery store is GST-free. The same loaf used to make a ham sandwich sold at lunch counter is taxable (as part of a prepared meal). Cold milk bought from a supermarket is GST-free. A takeaway coffee made with that milk is taxable. Plain flour, rice, and fresh fruit are GST-free. Flavoured milk, confectionery, biscuits, soft drinks, and ice cream are all taxable by specific rule.

Cafés, bakeries, delis, and mixed food retailers almost always sell both taxable and GST-free items. The point-of-sale system has to be set up to tag each product correctly. Relying on staff to apply GST manually at the register is where errors accumulate quarter after quarter.

Health service providers

A health service is generally GST-free where it is supplied by a recognised health professional (doctor, nurse, dentist, optometrist, physiotherapist, psychologist, and so on) and is generally accepted in the relevant profession as necessary for appropriate treatment. Administrative fees, missed appointment fees, and retail sales of products from the clinic are generally taxable.

An Ipswich GP practice is a common example. The clinical consultation is GST-free. A medical certificate for an employer is usually GST-free when provided as part of the consultation. A repeat prescription fee may be GST-free in some circumstances. A skincare product, vitamin, or orthotic sold from reception is taxable. A non-clinical report prepared for an insurer, employer, or solicitor is often taxable because it is not appropriate treatment. The practice has to separate clinical from non-clinical income in its accounting records.

Cosmetic procedures that are not necessary for appropriate treatment (purely aesthetic procedures, for example) are usually taxable, even when performed by a recognised health professional. The test is the nature of the service, not the title of the provider.

Education and training

The GST-free education category is narrower than most business owners assume. It covers education supplied by a school, university, registered training organisation, or similar recognised provider, where the course is of a type specified in the GST legislation. A privately run business skills course, a hobby course, or general coaching that does not fit within a recognised category is usually taxable.

A local tutoring business in Ipswich may be surprised to find that most of its tutoring is taxable. A registered training organisation delivering accredited trade courses is likely making GST-free sales. A private business coach running a workshop on social media marketing is almost certainly making taxable sales. The status of the provider and the nature of the course both matter.

Residential vs commercial property

Residential rent is input taxed. Commercial rent is taxable. The trap is in mixed-use properties and short-stay accommodation.

A shop with a residential flat upstairs, leased as a single package, usually requires apportionment between the taxable commercial component and the input taxed residential component. Short-term accommodation (hotels, motels, serviced apartments, short-stay holiday lets) is taxable, not input taxed, even though the premises are residential in character. The length and nature of the stay, and the services provided, determine the classification.

Second-hand goods and private sales

A GST-registered business selling second-hand goods is generally making a taxable sale, even if the goods were bought from a private individual with no GST on the original purchase. Special rules allow certain GST credits on second-hand goods purchased from unregistered suppliers, but the sale by the registered business is still taxable. Pawn shops, second-hand dealers, and businesses that take trade-ins need to understand this.

Tax invoice requirements

A tax invoice is a specific document that meets the ATO's requirements for claiming GST credits. Only a GST-registered business can issue one. A business that is not registered for GST must not label its invoices as tax invoices or show a GST amount.

When a tax invoice is required

If you are GST-registered and you make a taxable sale of $82.50 or more (GST-inclusive), you must provide a tax invoice within 28 days of the customer requesting one. For sales below $82.50, a regular receipt is sufficient, although many businesses issue tax invoices for every sale as a matter of course because it simplifies record-keeping.

Note: $82.50 is $75 plus 10% GST. The $75 figure also appears in a different context, the no-ABN withholding rule, which applies when another business pays a supplier that has not quoted an ABN. If the payment for a supply is more than $75 (excluding GST), the paying business must withhold 47% and remit to the ATO unless an exception applies. The two $75 thresholds are different but easy to confuse.

What a tax invoice must contain

Every tax invoice must include the following:

• The words 'tax invoice' displayed prominently.
• The seller's identity (business name) and ABN.
• The date of issue.
• A brief description of each item supplied, including quantity where applicable.
• The GST amount shown separately, or a statement that the total price includes GST (acceptable only if the GST is exactly one-eleventh of the total).
• The extent to which each sale is a taxable sale, if the invoice includes both taxable and GST-free or input taxed items.

For sales of $1,000 (GST-inclusive) or more, the tax invoice must also include the buyer's identity (name or business name) or ABN. Many point-of-sale systems do not capture buyer details by default. Transactions at or above $1,000 where the buyer wants to claim a GST credit need the POS workflow to collect this information.

If you are not registered for GST

If you are not registered for GST, do not label your invoices as tax invoices, do not show a GST amount, and do not charge GST. Including 'tax invoice' or a GST line on a non-registered invoice is a compliance breach that can mislead the buyer into claiming a GST credit they are not entitled to. Some unregistered sole traders include a line such as 'No GST has been charged' to make the position explicit.

Mixed supplies

A mixed supply is one invoice covering items with different GST treatments. A café sells GST-free basic bread and taxable prepared sandwiches. A health clinic charges a GST-free consultation fee and sells a taxable vitamin. A rural supplier sells GST-free livestock feed and taxable farm equipment. Most businesses with more than one product line will have mixed supplies at some point.

For mixed supplies, the GST treatment of each component has to be identified on the invoice. You can either show the GST per line item (which is what most accounting systems do automatically once products are coded correctly), or identify which items are taxable and total the GST at the bottom.

The key discipline is in the product setup, not the invoice template. If your inventory system has each product tagged with the correct GST code, your invoices will classify correctly by default. If products are miscoded at setup, every invoice inherits the error. Reviewing GST codes at stocktake, or when new products are added, prevents the problem rather than correcting it later.

Composite vs mixed supplies

A subtlety worth knowing: some packages that look mixed are actually single composite supplies where one element is incidental to the main supply. A flight with a complimentary meal is a single taxable supply (domestic transport), not a mixed supply. A GST-free health consultation that includes incidental bandages or basic medications is a single GST-free supply, not a mixed one.

The test is whether the separate components are integral to a single supply or are genuinely distinct items the customer could have chosen separately. Most ordinary commercial situations are clear, but specialist industries (healthcare, education, hospitality) sometimes need careful analysis. When in doubt, treat the components separately and document the reasoning.

The one-eleventh calculation and GST rounding

GST-inclusive and GST-exclusive pricing produce different calculations. Both are valid, but the method has to be consistent.

If the price is GST-exclusive, multiply by 1.1 to get the GST-inclusive price. A $500 GST-exclusive sale becomes $550 GST-inclusive, with $50 of GST.

If the price is GST-inclusive, divide by 11 to get the GST amount, or divide by 1.1 to get the GST-exclusive price. A $1,100 GST-inclusive sale contains $100 of GST on $1,000 of GST-exclusive value.

For consumer-facing businesses, GST-inclusive pricing is the norm and often required by consumer protection law (prices advertised to consumers must be GST-inclusive). For business-to-business transactions, GST-exclusive pricing is more common because both parties are GST-registered and the GST nets out through input tax credits.

Rounding

Where GST produces fractional cents, rounding rules apply. The two options are the taxable supply rule (calculate GST on each taxable item separately, then round each amount) and the total invoice rule (sum the GST-exclusive value of all taxable items, calculate GST on the total, then round once). The total invoice rule is simpler and is what most accounting software uses by default. Pick a method and apply it consistently.

The supplier and the buyer do not have to use the same rounding rule, which means a buyer's claimed GST credit may differ from the supplier's reported GST by a cent or two on any given invoice. This is normal and not a compliance issue.

Common mistakes that show up in BAS reviews

Claiming GST credits on GST-free or input taxed purchases

The most common error. Bank fees, residential rent, basic food, most health services, and certain government charges do not include GST. Claiming an eleventh of these amounts as a GST credit is a straight overclaim. Accounting software with GST codes set correctly avoids this, but many small businesses process transactions in the bank feed without checking each line. A quarterly review before BAS lodgement picks up most of these.

Claiming full GST credits on mixed-use expenses

A ute used 70% for business and 30% privately only supports a GST credit of 70% of the GST paid. A phone bill split between business and private use needs apportionment. The same logic applies to internet, power in a home office, and any other mixed-use expense. Claiming the full amount and then reducing the business portion for income tax purposes is not the same as apportioning the GST credit, and the ATO treats them separately.

Treating GST-free sales as out-of-scope

GST-free sales still have to be reported on the BAS. They appear at label G3 on the full BAS or in the GST-free sales line in software. Some businesses incorrectly leave GST-free sales off the BAS entirely, which misstates total turnover and can affect future GST registration thresholds and the accuracy of ATO data matching.

Missing GST on taxable sales

This happens when a business is newly registered and continues using old pre-registration invoice templates, or when a point-of-sale system is not updated after a product reclassification. The business is still liable for the GST on the sale even if it was not charged to the customer. Recovering the GST from the customer after the fact is often commercially difficult, so the amount comes out of margin. Reviewing the invoice template and product codes on the day of registration is the fix.

Confusing GST-free and input taxed

A residential landlord who treats rent as GST-free and claims GST credits on the property management fee is making two errors at once: rent is input taxed (not GST-free), and no GST credits are available on expenses related to input taxed activities. The ATO catches this in data matching against rental bond authority records.

When to get advice

Most GST issues are solved by having accounting software set up correctly from the start, and reviewing classifications when the business changes (new product line, new service offering, change in business model). A registered tax or BAS agent can set this up once and the system handles most transactions from there.

Specific situations where advice matters more:

• A business moving into a new category (a café adding catering services, a GP adding cosmetic procedures, a shop adding online international sales).
• Mixed supplies that are not obvious, particularly in healthcare, education, and hospitality.
• Large or unusual one-off transactions (sale of a going concern, sale of commercial property, export transactions above ordinary volumes).
• Buying or selling residential property in a context where the new residential premises rule might apply.
• Any ATO query about GST treatment or a BAS adjustment notice.

For Ipswich business owners, the most common situations we see are food businesses that have not reviewed their GST codes since they were set up, health practices with unclear classification of retail vs clinical income, and property owners uncertain about short-stay vs residential treatment. All of these are solvable, but they reward a structural review rather than quarterly patching.

Talk to Wiseman Accountants

GST is a system that rewards getting the setup right. If your accounting software is coded correctly, your invoices carry the right information, and your product or service categories are classified accurately, most BAS periods become routine. Where the setup is wrong, the errors compound quarter after quarter. If you have doubts about how your sales are classified, or if your business has moved into new territory since GST was set up, Wiseman Accountants can review your position and make sure the foundations are right.

This article provides general information current as at April 2026 and does not take your personal circumstances into account. GST rules have specific tests that depend on the nature of the supply and the parties involved. Speak with a registered tax or BAS agent before acting on any of the points raised.